Amajor difference between catastrophism and uniformitarianism is catastrophism supports rapid changes on the earth and a young age of the earth while uniformitarianism requires long times for changes to be significant and thus a very old earth uniformitarianism explains the young age of the earth by suggesting that while processes have not changed over time, the rates of processes may vary significantly uniformitarianism does not allow for catastrophic events while catastrophism is based on the assumption that they are the major forces of change in the earth catastrophism requires all changes on earth be due to unpredictable events that cannot be explained while uniformitarianism proposes that all events are predictable